Abstract: This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals,such as quantum dots and wires,which often contain tens of thousands of atoms.The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments.We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape.Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.

Key words: electronic structure, semiconductor, nanocrystals